Container having means for preventing escape of fluid therefrom where a shaft enters the same



Dec. 24, 1963 J. J. LENNON CONTAINER HAVING MEANS FOR PREVENTING ESCAPE OF FLUID THEREFROM WHERE A SHAFT ENTERS THE SAME Filed Aug. 22, 1961 152111323303 Joian J? Lemzozzl,

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United States Patent 3,115,34fl CGNTAINER HAVING MEANS FQR PREVENTHNG EdCAPE 9F FLUID THEREFRQM WHERE A SHAFT ENTER THE SAME John .l. Lennon, Winchester, Mass, assignor to Nettco Corporation, Everett, Massx, a corporation of Massachus-etts Filed Aug. 22, 1961, Ser. 'No. 133,247 4 tljlaims. (Cl. 277-59) This invention relates to a mechanism of the type wherein a driven shaft extends through the Wall of a container and operates a device within the same and means are provided where it enters the container wall for packing the shaft relatively to the interior of the container. The object of the invention is to provide a construction wherein a barrier of inert liquid is maintained separating those surfaces of the packing means which are exposed toward the interior from the interior spaces of the container. An example of such a mechanism is a mixer or agitator wherein the shaft carries a stirrer or impeller.

My invention will be well understood by reference to the following description of an illustrative embodiment thereof shown by way of example, wherein:

FIG. 1 is a partially sectioned and partially broken away elevation of an agitating or mixing machine illustrative of the invention; and

FIG. 2 is a vertical section on a larger scale of a portion of P16. 1, taken in a different plane which misses the fastening studs of FIG. 1.

Referring to PEG. 1, the mechanism shown is conventionfl except for the parts detailed in FIG. 2, and will be understood from inspection. Suffice it to say that a container it) has an opening 112 closed by a cover plate 14 through which extends an input shaft 16 which carries at its lower end an impeller (not shown). The input shaft is driven by suitable intermediate connections, not necessary to describe in detail, from electric motor 18. Herein a housing 26 with cover 22 and supported by cover plate id accommodates a bearing 24 for the shaft, and beneath the same a seal of the radial or mechanical type comprising an unbroken annular element fixed to the shaft and a confronting annular element carried by the housing, the two having finished surfaces contacting one with another in a radial plane and forming a seal between the interior of the container and the shaft. Various constructions of this kind of seal are well known and available commercially. Detailed illustration and description are unnecessary. They are examples of a packing for the shaft, but a packing of superior elficiency as compared for example with a stuffing box.

In accordance with my invention a barrier of inert liquid is maintained between the packing means and the interior of the container. As an example of its utility I may cite the case where a polymerization is carried out in the container. Sometimes solid polymeric particles are formed which are suspended in a gaseous phase in the upper part of the container. These may be deposited on the walls of the container (a figurative comparison with boiler scale may be suggested) and also on the downwardly exposed portions of the seal 26. Relatively frequent overhauling and earlier eventual replacement of the seal is then required.

The preferred mechanism for maintaining a barrier of inert liquid between the inwardly presented surfaces of the seal and the interior of the container which is here illustrated comprises a cup 28 (in effect a downward extension of housing 2t) below the position of seal 26) having a rim 3%? secured to the inner surface of the cover 1 through the bottom of which cup the shaft 16 extends. A downwardly inclined, frusto-conical lip seal 32 (FIG. 2)

is provided. This is not a seal in the sense that it is efficient to prevent any passage of liquid, but it retards its flow. Liquid can leak or seep through.

The interior of the cup communicates with an open topped liquid receiver, herein a second cup 34 which is mounted on the shaft 16, and into which the cup 28 exends downwardly. Seepage from the first cup 28 will enter the second cup 34 and partially fill it.

A conduit 36 from the exterior controlled by valve 38 permits liquid to be supplied to cup 28, and a conduit 40 controlled by valve 42 provides for the release of air therefrom. When liquid begins to be discharged from conduit 44 the cup is filled. Some liquid will have escaped to cup 34 and form a fluid seal. If some has spilled over the edge that is immaterial.

It should be noted that we do not have in FIG. 2 a concentric U tube wherein two hydraulic heads are opposed as in some types of differential pressure gage. When the cup 28 is full there is no atmospheric pressure on its contents. There is such a pressure on the contents of external cup 34. The pressure in cup 28 of only a few inches of liquid is opposed by a smaller liquid head plus a gas pressure equivalent to many inches of liquid and the cup 28 remains chock-a-block full so long as any liquid surface is exposed in the outer cup 34. A constant volume of barrier liquid is trapped and maintained in cup 28.

l have also referred to the cup as being chook-a-block full with the liquid contacting the downwardly facing portions of the sealing mechanism. Obviously in most instances a slight volume of air trapped at the top of the liquid column within cup 28 would not make any significant difference. A liquid barrier would be retained and the trapped air would exert no significant pressure.

The bottom of cup 28 operates with collar 44 on the shaft to provide for vertically supporting the shaft when it is lowered to permit removal of the seal over the upper end of the shaft section in the manner known in the art.

Another application of the mechanism is found in situations Where a noxious or corroisve gas accumulates in the container.

While usually the packing will be of the mechanical, radial seal type, the mechanism may be used in connection with a packing in the nature of a stufling box, less efficient as a seal. In fact a stufiing box is sometimes characterized as a controlled leakage mechanism. Obviously by providing a predetermined head in conduit 36 with valve 38 open any leakage through a smiling box would be of harmless liquid instead of noxious gas.

The liquid has been referred to as inert. This means that it does not adversely affect to any substantial degree the elements of the construction with which it makes contact and does not objectionably react with or mix with the gases or vapors toward which it is presented as a barrier. A certain solvent capacity for the vapors and gases involved may in some cases be tolerated. The liquid which forms the barrier may be replenished or flushed out and replaced from time to time by suitable tending of the conduits 36 and 49, either routinely or extemporaneously.

It will be apparent that the invention may be embodied in other specific forms without departing from the spirit or essential attributes thereof, and the present embodiment should therefore be considered in all respects as illustrative and not restrictive, as is in fact clear in several matters from the description itself. Reference is to be had to the appended claims to indicate those principles of the invention exemplified by the particular em bodirnent described and which it is desired to secure by Letters Patent.

I claim:

1. In a mechanism of the type wherein a driven rotary shaft extends through'a wall'of a container and operates a device within the same and wherein it is desired to prevent the escape of fluid from within the container at the point of entry of the shaft, the improvement comprising a cup supported by the container wall and having an open top and a bottom through which the shaft extends and packing means between the shaft and the container Wall closing the annular portion of the open top around the shaft, a second and open topped liquid receiver within the container, the cup and receiver communicating adjacent their bottoms and controllable means accessible at the exterior of the container for supplying inert liquid to and exhausting aeriform fluid from the 'cup to permit the same to be filled with liquid to provide a liquid barrier between the interior spaces of the container and the packing means. i

2. The construction of claim 1 wherein means are provided for retarding flow of the inert liquid from the cup into the liquid receiver.

3. In a mechanism of the type wherein a driven rotary shaft extends through a wall of a container and operates a device within the same and wherein it is desired to prevent the escape of fluid from within the container at the point of entry of the shaft, the improvement comprising a cup having a rim secured to the container wall Where the shaft traverses the same and through the bottom of which the shaft extends, packing means closing the annular portion of the top of the cup around the shaft, a second cup carried by the shaft below the first cup into the 4 upper portion of which second cup the lower portion of the first extends, and controllable means accessible from the exterior of the container for supplying inert liquid to and exhausting aeriform fluid from the first cup to fill the same with liquid substantially to the level of the downwardly presented surfaces of the packing means.

4. In a mechanism of the type wherein a driven shaft extends through the Wall of a container and operates a device within the same and means are provided where it enters the container wall for packing the shaft relatively to the interior of the container to prevent escape of fluid from the container at the point of entry of the shaft, the improvement which comprises a vessel trapping and maintaining a quiescent body of inert liquid of constant volume which mass is located around and in contact with a portion of the shaft just inwardly of the container wall, and extends outwardly past the periphery of the opening of the container walls and extends from beneath into close opposition to the downwardly presented surfaces of the packing means throughout the area thereof through which fluid could leak and means controllable at the exterior of the container for filling said vessel.

References Cited in the file of this patent UNITED STATES PATENTS 2,215,449 Alexander et a1. Sept. 24, 1940 2,982,417 Durrell May 2, 1961 3,017,191 Patterson Ian. 16, 1962 

1. IN A MECHANISM OF THE TYPE WHEREIN A DRIVEN ROTARY SHAFT EXTENDS THROUGH A WALL OF A CONTAINER AND OPERATES A DEVICE WITHIN THE SAME AND WHEREIN IT IS DESIRED TO PREVENT THE ESCAPE OF FLUID FROM WITHIN THE CONTAINER AT THE POINT OF ENTRY OF THE SHAFT, THE IMPROVEMENT COMPRISING A CUP SUPPORTED BY THE CONTAINER WALL AND HAVING AN OPEN TOP AND A BOTTOM THROUGH WHICH THE SHAFT EXTENDS AND PACKING MEANS BETWEEN THE SHAFT AND THE CONTAINER WALL CLOSING THE ANNULAR PORTION OF THE OPEN TOP AROUND THE SHAFT, A SECOND AND OPEN TOPPED LIQUID RECEIVER WITHIN THE CONTAINER, THE CUP AND RECEIVER COMMUNICATING ADJACENT THEIR BOTTOMS AND CONTROLLABLE MEANS ACCESSIBLE AT THE EXTERIOR OF THE CONTAINER FOR SUPPLYING INERT LIQUID TO AND EXHAUSTING AERIFORM FLUID FROM THE CUP TO PERMIT THE SAME TO BE FILLED WITH LIQUID TO PROVIDE A LIQUID BARRIER BETWEEN THE INTERIOR SPACES OF THE CONTAINER AND THE PACKING MEANS. 